1. Field of the Invention
The present invention relates to a compound image-forming method and compound image-forming apparatus having another application besides a facsimile application.
2. Description of the Background Art
Together with the widespread use of digital copiers in recent years, there has been proposed a compound copier (also called a multifunctional peripheral or MFP), which has a facsimile function in addition to a copying function. An MFP has functions for processing an input operation and an output operation in parallel, such as a copying function for reading and printing a document, and a facsimile function and e-mail transmission function for reading and sending a document. Recently, MFPs have been equipped with functions that enable a plurality of output operations to be selected relative to an input. For example, there are functions for sending a facsimile, carrying out a printing operation to obtain a duplicate cope, and storing information in an HDD (hard disk drive) via a one-scan operation. For this reason, it is common to perform reading using the imaging format and formatting format that is the easiest to handle by the various types of functions. JPEG can be cited as typical example of this for color images, and MMR can be cited as a typical example of this for black-and-white images.
Since color is emphasized in MFPs, JPEG will be explained hereinbelow.
For example, problems arise with the copy function and facsimile function of an MFP, which has hardware for using JPEG to compress an image read using an RGB format.
<Copy Function>
Since it is not possible to carry out compression or decompression with JPEG until the reading of an entire page is complete, it is difficult to achieve fast copying speed or to speed up the time between pages. This is especially noticeable with a long document.
<Facsimile Function>
Since it is not possible to carry out compression or decompression with JPEG until the reading of an entire page is complete, the start of transmission for the top page is delayed, and communication delays occur between pages. This is especially noticeable for long documents. In a worst case scenario, communications are cutoff.
Furthermore, in recent years, for security and resource conservation reasons, it has become the practice to display and check an original image on the operation panel prior to printout or transmission, carrying out the output operation thereafter. Further, image data is transferred to a server where it undergoes historical management. Preview and thumbnail images are created for this purpose. Furthermore, since there are no time restrictions for creating a preview or thumbnail image, users generally like to create an image file using a one-page format.
However, when copying or faxing a long document, outputting after reading has been completed takes time. Accordingly, Japanese Patent Laid-open No. 8-116525, for example, proposed dividing output times to coincide with the size of the printing paper.
However, the problem with this prior art is that processing takes a long time when the compression system is not able to partially decode a compressed image.
Technologies related to the present invention are also disclosed in other Japanese Patents, e.g., 2004-048148, 2004-349858, 2005-223702, 2005-244616, H09-036749 and H11-341241.